We’ve all experienced the sense of being familiar with somebody without knowing their name or even having spoken to them. These so-called “familiar strangers” are the people we see everyday on the bus on the way to work, in the sandwich shop at lunchtime or in the local restaurant or supermarket in the evening.

But while many researchers have studied the network of intentional links between individuals—using mobile phone records for example—little work has been on these unintentional links which form a kind of hidden social network.

Today, that changes thanks to the work of Lijun Sun at the Future Cities Laboratory in Singapore and a few pals who have analysed the passive interactions between 3 million residents on Singapore’s bus network (about 55 per cent of the city’s population). […]

Study revealed that about 85 per cent of these repeated encounters happen at the same time of day and that individuals were more likely to encounter familiar strangers in the morning than the afternoon.